【M35 Cobalt Superhard High Speed Steel】: ISI M35/1.3243/SKH55/M35 steel is a kind of high speed steel containing cobalt, which has the characteristics of high wear resistance, high pressure resistance and sintering resistance. 【100 extra-long warranty period】：If you have any questions about the product, please contact us and we will answer you within 12 hours. If the hexagonal handle breaks, refund or replace for 100% . 【Unibit step drill bit compatibility 】：Unibit step drill bit can quickly and smoothly drill holes of different diameters, such as stainless steel, aluminum, wood, plastic board (the board must be thinner than the height of the step drill) 【M35 four spiral groove】: Step drill bit for metal four cutting blade design. Faster, smoother cutting and easier separation of sawdust. 【13 Sizes :Including】:Step bit the bit contains sizes ranging from 1/8” to 1/2”. Common sizes 1/8”, 3/32”, 3/16”, 7/32”, 1/4”, 9/32”, 5/16”, 11/32”, 3/8”, 13/32”, 7/16”, 15/32”, 1/2”, total 9 sizes,step bits For your everyday DIY needs 【TiAlN】:TiAlN coating is a new coating material in recent two years.ndustrial-grade construction ensures durability and longevity It has high hardness, high oxidation temperature, good thermal hardness, strong adhesion, low friction coefficient and low thermal conductivity coefficient. M35 Four Spiral Flute Step Drill Bit Set1/8"-1/2" （ 13 Sizes ）, 1/4" Hex Shank Drill , impact resistant M35HSS unit stepper bit,brocas para metal step drill bit for metal unibit step drill bit step bits for metal step drill bit for stainless steel, wood, aluminum, plastic